Train dispatching system for railroads



Sept. 29, I936. B. J. SCHWENDT 2,056,145

TRAIN DISPATCHING SYSTEM FOR RAILROADS Filed Nov. 17, 1'92? 2 Sheets- Sheet 1 m lk mm W @E i 5 62 ii or z I z 1.. a O j a fl mo h. m: X: n. I

R V N l I l I I I l l l l I I I I l I I I I I l I I I l I I I I I I I I I l l l I I I l I I l I l I l l I I BY Kym //i ATTORNEY Sept. 29, 1936- B.- J. SCHWENDT I TRAIN DISPATCHING SYSTEM FOR RAILROADS 1 Filed Nov. 17, 1927 2 Sheets-Sheet 2 v IN E TOR BY W ATTORNEY Patented Sept. 29, 1936 "UNITED STATES TRAIN DISPATCHING SYSTEM FOR RAILROADS Bernard J. Schwendt, Cleveland, Ohio, assignor to General Railway Signal Company, Rochester, N. Y.

Application November 17, 1927, Serial No. 233,845

26 Claims.

This invention relates to train dispatching systems of the type in which the dispatcher communicates with the engineers, that is dispatches the movement of trains, through the medium of wayside signals.

In a train dispatching system of the kind mentioned, a single train dispatcher preferably has great economy in line wires would result if the same circuit wires could be used for the control of signals at, and the indication movement of trains by, each and every one of the wayside stations.

In accordance with the present invention, it is therefore proposed to control the wayside signals, operate the switches and the like, of all the waystations in a particular stretch of track, through the medium of code responsive selector relay or relays of any suitable and Well known construction; whereby a. particular trafiic controlling device may be operated to a particular position in response to the transmission of a particular code of impulses to all of the various Wayside stations, suitable code responsive selectors being provided at each wayside station for this purpose.

The operation of any one of a plurality of wayside signals and power operated switch machines through the medium of a single control circuit and a plurality of distinctively responsive code responsive selectors as just explained, is a comparatively simple problem. The principal difiiculty encountered in dispatching the movement of trains through the medium of wayside signals resides in the provision of means for manifesting to the train dispatcher the progress of the various trains along the track over comparatively few line wires. fact that automatically operated calling keys and code responsive selectors alone can not be used, for if the progress of trains is reported to the train dispatcher by the condition of occupancy of the various track sections, it is possible that two or even three track sections'may become occupied or unoccupied at the same in- This difficulty arises from the stant and if this simultaneous change in traflic conditions were transmitted to the train dispatcher by distinctive codes of impulses, a jumbled up code would result. In other Words provision must be made whereby it is impossible for a plurality of codes to be transmitted to the dispatchers oifice simultaneously.

It is therefore proposed in accordance with the present invention to not only control the wayside signals and switch machines of all of the various waystations by distinctive codes received by specific code responsive selector relay or relays overthe same line circuit, but to transmit over the same line circuit information to the dispatchers ofiice as to the occupancy of various track sections, positions of signals, the positions of track switches, derails, and the like, and to provide suitable lock-out means, whereby if conditions are such that two distinctive codes are attempted to be transmitted at the same time, one of these indications is entirely held up until the other has been transmitted, after which the lock-out apparatus will permit the said one code to be transmitted to the dispatchers ofiice over the same circuit.

Other objects, purposes and characteristic features of the invention will in part be apparent from the accompanying drawings, forming a part of this application, and will in part be described in the specification hereinafter.

In describing the invention is detail reference will be made to the accompanying drawings:-

The main drawing is contained on two sheets and is designated Figs. 1A and 13, respectively. The portion of the drawing designated Fig. 1A illustrates conventionally apparatus located in the dispatchers oflice and embodying the'present invention, and the drawing designated Fig. 13 illustrates conventionally apparatus of the train dispatching system embodying the present invention located along the trackway; and

Fig. 2 shows a slight modification of the invention. I

In order to more readily understand the detail features of the present invention as more specifically pointed out hereinafter it is deemed expedient to first briefly point out what the various features are. In order to transmit distinctive codes over a single line circuit connecting a certain waystation with the dispatchers ofiice, say in response to the dropping of a track relay, it is necessary to operate a so called calling key or code transmitter; In order to be sure that this code is actually transmitted to the dispatchers tower it is proposed in accordance,

with the present invention to provide a stick relay which controls the motor for operating this calling key, and it is proposed to arrange the {circuits so that this stick relay will remain energized until the code has actually been transmitted to the dispatchers office, after which the stickrelay willdrop and again stop the motor driven calling key or' code transmitter.

In order to prevent calling keys of the several waystations to transmit codes over the same. line circuit at the same time I have provided a lock-out circuit or pilot circpit w hereby only one of the waystation calling keys may :transmit a distinctive code to the train dispatcherjs office at one ,time. In the particular arrangement shown this lock-out combination comprises a plurality of relays each having an upper and lower winding, of which all cf the lower windings are connected in series. If a particular waystation apparatus is in condition Lto transmit .a .codeto the dispatchers ofiice the cuppercwinding of rthe relay of that particular waystation is. energized by currentwhich tends .to causethe normally energized relay to assume .its retracted position. When this occurs the loweriwinding .of this relay "is cut out of the pilot wire orxlock-out circuit and an additional source .of current is put in this. lock-out circuit. Withthisiadditional voltage in the circuit-the current flow in this circuit is sufficient to maintain. all .of the other. double winding pilot relaysenergized in spite .of the application of opposing currenttotheir .upper winding, so that .even though .the upper winding of any one of theiotherrelays is energized with neutralizing .currentsuch relay will not assume its de-energized position. The arrangement is thus such that. the dropping of one of these lock-out relays to their retracted position will cause the look-out -.cir.cuit to becnergized by-excess current, thereby preventing dropping of any other lock-out relay. 'The arrangement-is such that a code can not -be transmitted from a waystation to the-dis- ..patchers-oifice unless such lock-outrelay assumes its de-energized position.

Another -of the features of thewaystation apparatus resides in the provision of a synchronizing relay which can only close thecoding circuit :for.thatparticular waystation at the beginning of a cycle of operation of the code transmitter-and .this synchronizing relay is also constructed and controlled so .as to again open this code trans- --m-itting circuit at the end of the transmission of a distinctive code of impulses.

The waystation apparatus also includes-a holdover-relaywhichiisconstructed and operated so :that 'it is in cooperation with a hold-over cam of the code transmitter and will stop the code transmitterat the end of the first cycle in which a code is actually being transmitted to the dispatcheflsoffice. These various essential characteristicfeatures should be borne in mind in connection with the following detailed description of the invention.

General description Although the present invention in practice would, as a rule, be applied to a stretch of track having from 10 to 20 passing sidings or waystations,.only a portion of such stretch of track, and

a-portion of the associated apparatus, has been .shown in .the drawings. Referring to Fig. 13 a stretch of single trackO together with the adjacent ends of two passing sidings PS and PS of the railway (track have been shown. At each end DR and the track battery ll. nals associated with the track switch S have been of each passing siding is provided the usual track switch, those shown being designated S and S and these track switches are preferably operated by power operated switch machines SM having a corresponding exponent.

These track switches are provided with the usualdetector track circuit, theonefor the track switch S includes the detector track relay ZDR and a track battery l0, and the detector circuit for the track switch S includes the track relay The starting sigdesignated 2 and 2 and are set at the entrance to the detector track circuit for that direction -Ottraffic which they govern, and the entering signals have been designated I and I and are located at the. entrance of the detector track circuit for the direction in which they govern traffic. In-the same way, the starting signals for the track switch S have been designated 5 and 5 respeotively, andtheentering signals'have been designated -B and 43 Although, in-practice, there would as a general rule be a plurality of pairs -of intermediate sig-nals, 0nly the intermediate signals 3 and 4 have been shown. It should be noted that the signals for westbound traffic have been designated by odd -numbers,--whereas the signals for east bound trafiic have been designated by even numbers. The signal system embodying the signals shown is one of the absolute-permissiveblock type, and these signals are controlled in accordance with traflic conditions, the condition the control relay Z and the position of the switch machines 'SM, all in a-manner as-more particularly disclosed in the application of Sedgwick N. Wight Ser. rid-120,423 filed July 3, 1926, which correspends-to Australian'Patent No. 7,777 of 1927.

For the purposes-of the'present application the apparatus for controlling these various signals in accordance-with trail-"1c conditions has been emit- -ted,- and the superimposed control thereof in response to the energized condition of the control relay Z and the position of the switch machine =SM has been co-nventiona'lly shown by dotted lines. It should however-be understood that the present invention may be superimposed on any type of signal system, double track as well as single track. It may be pointed out here that the various relays associated with the track switch -S 'contain a reference letter having an exponent I, and that the corresponding relays associated with the track switch S are designated by like reference characters having the distinctive exponent '2.

In 'the'particular embodiment of theinvention illustrated the usual telephone line TEL is simplexed by the provision of impedance units l5, l5 15', I5 etc.,-to the midpoint of which suitable circuit portions are connected. In addition to this telephone line 'IEL there is-provided a common return wire C, and a lock-out wire LO which extend throughout the entire stretch of trackway controlled by a-particular train dispatcher. It

may be pointed out here that theswitch machines SM and SM are provided with racks I6 and IE which uponmovement of such switch machine from one extreme position to the other,

causes any suitable number, such as two taps to be sounded in the telephone or loud speaker T located at the dispatchers oifice when the switch machine starts its operating stroke and again sounds two-more taps when such switch machine has completed its stroke. This is accomplished by intermittently connecting the battery IT across the telephone line TEL.

In the dispatchers tower or ofiice conventionally shown by the dotted rectangle DT is preferably suitably mounted, as on a table, a miniature track layout corresponding to that of the portion of the railway system over which that particular dispatcher has supervision. The portion of the miniature track layout shown comprises a single track section corresponding to the single track section 0 shown in Fig. 1B of the drawings. On this miniature track layout are provided, as for instance for the switch S a red light R and a green light G to indicate the occupancy and unoccupancy respectively of the detector track circuit associated with the switch S Similarly lamps R and G are provided at the exit end of the single track section 0. With both of these lamps extinguished unoccupancy of the detector track circuit is manifest, with the lamp R lighted occupancy of this detector track circuit is indicated and when both the red lamp R and the green lamp G are lighted manifests that the detector track circuit has been occupied and has since been cleared. These lamps may be colored as desired, and the lamp G may be entirely omitted if desired.

Dispatchers control me'chanism.Referring to the apparatus for controlling the switch machines and signals associated with the switch S and bearing in mind that with the relay Z energized to its normal position the switch machine SM will assume its normal position, and if so, the continued energization of the relay Z to normal will clear the signals or 2 depending upon whether the signals 5 and 5 are at clear or stop, all of which has been described in detail in the application'of Wight above referred to. All that need to be considered in the present application to understand the application of the present invention is the manner in which the control relay Z is controlled from the dispatchers ofiice DT.

In the dispatchers ofiice there are provided cranks or levers LN LS and Ll-l which if successively separately operated through a complete cycle will cause the code responsive relay CCR at the way station S to apply the positive terminal B of a suitable battery to the wires 20, 2| and 22 respectively. That is, if the lever LN is operated through its cycle the wire 23 is momentarily ener gized therebypicking up the normal route relay NR if the lever LS is operated through a complete cycle the code responsive selector CRR will momentarily energize the siding route relay SR which will thereafter be maintained energized through a stick circuit; and if the stop lever LI-I is operated through a complete cycle the stop relay ST is momentarily energized, thereby dropping the relay Z and momentarily opening the stick circuit of the normal route relay NR or siding route relay SR depending upon which one of these route relays is energized at the time. The pick-up circuit for the normal route relay NR completed upon operation of the lever LN may be traced as follows: beginning at the terminal B of a suitable source of direct current, wire 25, selector contact 26 of the selector CRR.--, wires 26 and 21, winding of the route relay NR wires 28, 29 and 3|], to a common return wire C connected to the other terminal of said source of current. With this route relay momentarily picked up the following stick circut is completed:beginning at the terminal B, wires 25 and 3|, back contact 32 of the stop relay ST, wires 33 and 34, back contact 35 of the siding route relay SR wire 35, front stick contact 31 of the normal relay NR,

wires 38 and 21, winding of the route relay NR wires 28, 29 and 30, to the other terminal N of said source. The various code responsive selector relays forming elements of the present invention may be of any suitable construction, such for instance as shown in the patent to Field #1343,- 256 dated June 1 5, 1920 and their specific construction does not form a part of the present invention, the present invention merely including such selectors as elements thereof.

Assuming for the moment that the relays NR SR and ST are in their normal de-energized condition, the pick up circuit completed for the siding relay SR when the lever LS is operated, may be traced as follows:beginning at the terminal B, wire 25, selector contact 40 of the code responsive selector GER, wires 2| and 4|, winding of the siding route relay SR1, wires 42, 29 and 30, to the common return wire C connected to the other side of the source containing terminal B. With this siding route relay SR once energized the following stick circuit is completed to maintain it energized:--beginning at the terminal B, wires 25 and 3|, back contact 32 of the stop relay ST, wires 33 and 43, back contact 44 of the normal route relay NR wire 45, front stick contact 46 of the siding route relay SR wires 41 and 4|, winding of the siding route relay SR wires 42, 29 and 30, to the common return wire C.

It should be noted that the stick circuits for both of the route relays NR and SR include the back contact 32 of the stop relay ST, so thatmomentary energization of the stop relay ST in response to operation of the lever LH causes the stick circuit for the route relays NR or SR depending upon which one is energized to be momentarily broken thus causing such route relay to drop. The energizing circuit for the stop relay ST comprises the following:-starting at B, wire 25, selectors contact 48 of the code responsive relay CRR wire 22, stop relay ST, wires 49 and 3|], to the common return wire C.

Operation of dispatchers control mechanism Let as assume that the dispatcher wishes to allow a train standing on the siding of passing siding PS to move eastwardly in the single track section 0, and in order to do so wishes to operate the track switch S to the take-siding position.

which will close the selector contact 40 of the selector CPURP, but which code will not close any other selector contact of the entire system. This will cause the siding route relay SR to be picked up and stuck up for reasons already given and whereby close the following circuit for the control relay Z ;-beginning at the terminal B, contact 56 of the siding route relay SR in its raised position, wire 5|, contact 52 of the route relay NR in its lower position, wire 53, back contact 54 of the stop relay ST, wire 55, winding of the relay Z wire 56, back contact ill of the stop relay ST, wire 58, contact 59 of the route relay NR in its lower position, wire 60, contact 6| of the route relay SR in its raised position, to the negative terminal N of the source containing positive terminal B. With this circuit completed the control relay Z will assume its left hand dotted position,

and will thereby operate the switch machine SM to the take-siding position through circuits conventionally shown by a dotted line 62. If the switch machine is operated rack l 6 intermittently applies direct current across the telephone line TEL through the following partial circuit: starting at one telephone wire, wire 63, battery l1, wire 64-, rack I6 contact 65, wire 66 connected to the other wire of said telephone line. This application of potential to the telephone line will cause a click in the telephone or loud speaker T located in the dispatchers office, two such clicks being given when the switch'machine is started and two more clicks being given after the switch machine has completed its operating and locking stroke. Assume that the starting signals 5 and 5* at the exit end of the single track section 0 are both at stop, the starting dwarf signals 2 is cleared as soon as the switch machine SM has assumed the take-siding position, and the train may then proceed into the single track section 0.

Let us now assume that the dispatcher wishes to return the track switch S to the normal main track position. In this case it will not be necessary for the operator to first operate the stop lever LE to effect de-energization of the relay Z, but he may operate the normal lever LN and thereby de-energize the route relay SR energize the route relay NR and cause the control relay Z to assume its main track energized position. That is, operation of the normal lever LN causes the pick-up circuit for the normal route relay NR heretofore traced, to be completed, thereby causing the stick circuit for the siding route relay SR which relay at this time is still stuck up through its stick circuit, to be broken at thecontact 44 of route relay NR so that the route siding relay SR assumes its retracted condition and thereby allows the stick circuit for the route relay NR heretofore traced, to be completed. With the normal route relay NR picked up and stuck up, the following circuit for energizing the control relay Z to its normal straight track position, in which current flows in the reverse direction from that which was flowing when the relay Z was energized to the reverse position, to be completed;beginning at the terminal B, contact 50 of the siding route relay SR in its lower position, wire 16, contact 59 of the route relay NR in its raised position, wire 58, back contact 51 of the relay ST, wire 56, winding of the control relay Z wire 55, back contact 54 of the relay ST, wire 53, contact 52 of the route relay NR in its raised position, wire 11, contact 6| of the route relay SR in its lower position to the terminal N. The completion of this circuit causes the switch machine SM to be returned to its normal straight track position, and if the control relay Z is then de-energized by reason of momentary energization of the stop relay ST, due to operation of the stop lever LE all of the signals i, l 2 and 2 will again assume their normal stop position. It may be mentioned at this point that during the transmission of a distinctive code from the dispatchers office to a waystation, the code relay COR located in the dispatchers office is energized through one or the other of the various lever contacts 61, 68, or 69, as a result of which excess energy is applied to the look-out circuit LO, whereby all of the Various waystation transmitters CT are locked out, so to speak, so that the wayside apparatus cannot simultaneously transmit a code to the dispatcher. This feature will be described more in detail under the heading Operation of indicating and OS-ing mechanism.

Indicating 0r OS-i'ng mechanism.The indicating or OS-ing mechanism associated with the detector track circuit of switch S will, for convenience, only be described, and like parts of the apparatus associated with the detector track circuit of switch S will be assigned like reference characters having distinctive exponent. In the tower or dispatchers office is provided a code responsive relay CRR of which the selector contact 10 is closed when a code is transmitted thereto by the red code wheel RW, and the selector contact H of which is momentarily closed if code is transmitted by the green code wheel GW of the automatic calling key or code transmitter CT Obviously momentary closure of these selector contacts 10 or H will cause the relay RG or RR to be picked up and stuck up, and. thereby lighting the lamps G or R respectively. With the code transmitter CT are associated various auxiliary devices, such as, the red stick relay RS the green stick relay (3S the pick up relay PU the hold-over relay H0 the synchronizing relay SYN the green code cam relay GK and the red code cam relay RK.

The code transmitting machine GT is driven by the motor M and includes a stop cam SC, holdover cam H00 and a starting cam STC. As already mentioned in a general way, this system includes a lock-out circuit LO which includes a pilot relay PR for every waystation and code transmitter. Only two of these relays PR and PR have been shown. These relays, such as PR although they are only two position relays have polar armatures so that current of a particular polarity is required to pick up the various contacts shown and if current of reverse polarity of a sufficient value to neutralize the current of the lower winding is simultaneously applied to the upper winding thereof, the movable element of this relay together with its various contacts will assume their retracted position. It

may be pointed out at this time that all of theserelays PR. have their lower windings connected in series in the look-out wire L0 in stick fashion, that is these lower windings include in seri'es therewith the front contact of these relays; and further at the remote end of the section under the supervision of the dispatcher this lookout wire L0 is connected to the common return wire 0' as shown by the dotted line 13, also upon the dropping of one of these relays, as PR as by the application of neutralizing current to its upper winding, the lower winding is cut out of the lock-out circuit and the battery 14 is substituted therefor, all through the shifting of contacts 1'5 96 and 93 maining pilot relays PR to be energized by excess current, so that the application of neutralizing current to any one of them will not cause such relay to assume its retracted position.

Operation of indicating or OS-ing mechanism.The normal circuit for the various pilot or lock-out relays PR may be traced as follows: beginning at the battery 89 wires l3! and I39 located in the dispatchers ofiice, back contact 8| of the cut out relay COR, wires 82, L0 and 83, front contact 90 of the relay PR wire 85, lower winding of the relay PR wire 86, front contact 93 of the relay PR wires 88, L0 and 89, front contact 90 of the relay PR Wire 9 l, lower winding of the relay PR wire 92, front contact 93 of the relay PR wires 94 and LO, through the various other lock-out relays PR, conventionally shown by the dotted line 13, to the common return wire C connected through wire 95 to the negative terminal of the battery 89. In addition to this provision for the energization of the vari- This will cause the reous pilot relays PR. the upper winding of these relays, such as the relay PR is also normally energized through the following circuit:- beginning at the positive terminal B of a suitable battery, contact 96, wires 91 and 98, back contact 99 of the relay HO, wire I 2|, upper winding of the relay PR wire I22, back cont-act I23 of the relay HO, wire I24, contact I25 operated by the cam HOC, to the negative terminal N of said battery.

Let us now assume that a train has just entered upon the detector circuit containing the detector track relay BR, and has caused the contacts I06 and NH of this relay 5DR to assume their retracted position. This will cause the pick up relay PU to move its polar contact I62 to the reverse dotted position and thereby momentarily complete a pick-up circuit for the red stick relay RS which circuit may be traced as follows: beginning at the positive terminal B of a suitable battery, polar contact I62 engaging the one way contact I63 of the pick up relay PU wires I62 and I65 winding of the red stick relay RS to the negative terminal N of the said battery. With this red stick relay RS momentarily picked up the following stick circuit for this relay is completed;-beginning at the negative terminal N of the said battery, winding of the relay RS wires I65 and I66, front contact ID! of the red stick relay RS wires I08 and I69, and then through either of the following two branches; (1) wires I6? and III, and front contact II2 of the pilot relay PR to the terminal B, and (2) through wire H3 and normally closed contact I I4 of the stop cam SC to the terminal B. This stick relay RS is thus stuck up until its stick circuit is broken. It should be noted that the one way contacts I63 and H5 are pivotally supported at the pivot point H6 and that they are yieldably held in this position shown by the tension spring III. From this construction it is apparent that if the contact I02 moves from its normal position to its dotted position it engages only the contact I63, and if it is moved from its dotted position to its normal position it engages only the contact H5.

With the red stick relay RS stuck up as just explained, the code transmitter CT is operated through suitable reduction gearing (not shown) by the motor M, the energizing circuit'of which motor may be traced as followsz-beginning at the positive terminal B of a suitable battery front contact IE3 of the red stick relay RS wire [18 winding of the red code cam relay RK, wires H9 and I26, motor M, to the negative terminal N of said battery. The code transmitter CT is started upon its operating cycle in a direction as indicated by the arrow. Upon beginning a cycle of operation the starting cam STC of this transmitter GT first closes its contact I36, and immediately thereafter causes the hold-over cam HOC to reverse its pole changer contacts 96 and I25. The reversal of these contacts 96 and I25 causes the potential applied to the upper winding of the relay PR to be reversed, and since this current is in excess as to ampere turns or at least equal to that of the current flowing in the lower winding of this relay PR this relay PR. will assume its de-energized position. This will cause its lower winding to be entirely out out of the look-out circuit and the look-out circuit to be energized by excess current derived from the battery I4 which is now connected in series with the battery 8!! in the dispatchers oflice.

At substantially the same time that contacts 96-425 are shifted from normal, theicontact I30 operated by the starting cam STC closes a pick up circuit for the synchronizing relay SYN This circuit may be traced as fol1ows:-Starting at the positive terminal B of a suitable battery, contact I12 of the pilot relay PR in its deenergized position, wires I3I and I32, winding of synchronizing relay SYN wires I33 and I34, contact I36 operated by the starting cam STC to the negative terminal N of said battery. It should be noted that even though the pilot relay PR is now in its de-energized position the red stick relay RS still has its stick circuit completed through the stop contact II4 operated by the'stop cam SC. With the synchronizing relay SYN energized a code transmitting circuit through the red code wheel RW is completed, the red code cam relay RK being energized through the circuit heretofore traced. This code circuit may be traced as follows:beginning at the battery 86 located in the dispatchers tower DT, wires I31 and I38, battery I40, wire I4I, winding of the master relay MR, wires I42, I43, and I44 to the midpoint of the simplex impedance I5 of the telephone line TEL, through the two telephone wires in multiple to the balancing impedance I5", wire I45, front contact I46 of the synchronizing relay SYN wires I41 and I48. red code wheel RW, wire I49, front contact I56 of the relay RK, wires I5I and I52, to the common return wire C connected by wire 95 to the negative side of battery 86. The code transmitted by the red code wheel RW causes the necessary number and properly spaced impulses to be transmitted to close the selector contact 70 of the code responsive relay CRR in the dispatchers oflice, thereby picking up the red relay RR through wires I54 and I55. This relay BB is then stuck up through a stick circuit in cluding its own front contact I56, wire I51, the normal closed push'button contact I58, wire I59 and I55. With the relay RR energized the red lamp R is illuminated through the completion of the following circuit-starting at B front contact I66 of the relay RR wire IBI, red lamp R to the other terminal N. I

It should be noted that during this transmission of the distinctive code to: the tower the red stick relay RS depends for its energization on the contact I I4 operated by the stop cam SC. Near the end of the cycle of the operation of the code transmitter CT this stop cam SC momentarily opens the contact H4, thereby interrupting the stick circuit for stick relay RS and causing it to assume its de-energ'ized position. Dropping of the stick relay RS cuts energy off of the motor M and stops the code transmitter at the end'of the complete cycle. Just prior tothe completion of this cycle of operation of the code transmitter CT the holdove-r cam HOC returns the contacts 96 and I25 to their normal position, thereby reversing the flow of current in the upper winding of the pilot relay PR thereby causing this pilot relay PR which is a polar relay, to again assume its normal energized position, and thereby removing the excess energy formerly supplied by battery I4 and again connecting the lower winding of this relay PR in the look-out circuit L0. This picking up of the relay PR interrupts the energizing circuit for the synchronizing relay SYN thereby restoring this relay SYN to'normal. All of the code transmitting apparatus is new again in its initial and normal condition.

The operator has thus been informed by the illumination of the redlamp-R- that a train entered upon the,- detector track circuit associated with trackswitch S The operator may then, if he so desired, depress the push button 158 and again extinguish the lamp R it being assumed that he has taken the necessary action'in response to this train movement.

When the traina ain leavesthe detector track circuit containing track relay 511R the contacts I00 and 1-0! thereof will be returned to their normal position, thereby returning the pick-up relay PU to its .normalsolid line position. This movement of the contact 102 of the pick-up relay PU momentarily completes a pick-up circuit for the greenstick relay G S ,-whichn ay be traced as follows:beginning at the positiveterminal B of a battery, polar contact -,I-02,.oneway contact H5, wires I62 and i3, winding of the green stick relay GS? tothenegative terminal Not the said bat Fy- With re G3 n c ed up i wi b stuck up through the following cirouitzbeginningat the negative terminal N of the said bat.- te y w in of erela-rfis wi e I63 d i i ontfitick c es 5. o th re a G6 Wire d a th ou h th foll win wo b anch (,1) wire l,l l and contact :2 of the relay PR to positive terminal J3, and (2) wires I;6'l and I;l;3, ,and stop contact I L4, to the positive terminal With the ,green stick relay GS energized the motor n eenc d rel K are energize through the following ;circuit:.-beginning at the terminal f a suitable battery, back contact -I I8 of the red stick relay RS wire 110, front contact "I of the green stick relay .GS Wire 112, Winding of thegreen cam relay GK, wires 1 l3 and 1 20, motor M, to the other terminal N of said battery.

The function of transmitting the green code through the medium of :thegreencode wheelGW underordinary circumstances is the same as that of transmitting the red code already explained, exceptas to thespeoific cha acter of thecode, so that this need not he specifically described. This green code of course picks up the relay RG which in turn illuminates the ,green -lamp G ,corresponding parts and contacts associated with re.- lay RG have been assigned like reference characters with distinctive ,exponentsra as those associated with relay RR It may however be point,- ed out that the green code can not be transmitted until the red .code has been transmitted, this because the energizing circuit for the green code relay GK is carried through the back contact H8 of the red stick relay RS From this it is seen that if the red relay RS is stuck up, and the green relay GS is also stuck up thereafter but before {the red code has been transmitted, the transmission of the green code is'held in abeyance until the red code has been transmitted after which both of these stick relays RS and GS are tie-energized and this event no green code rans itted- As already pointed out heretofore, there is a possibility of two difierent detector track circuits becoming occupied at the same time, or for one to be occupied at the same instant another is cleared, or two detector track circuits to be cleared at exactly the same time, and for this reason the transmitting mechanism at two dif. ferent waystations may be initiated at substantially the same time.

In order to avoid two different code transmitto s C an m n co s simultan ou ly. the lock-out circuit L0 and the associated pilot relays PR have been provided. In order get a m e un r tandi of t is ock-out featu e of the presentinventionlet us assume that the detector track circuitassociated-with switch s -is being occupied byatrainat an instant when one of the other pilot relays, such as the ,pilot relay PR isinitsretracted o ondition, possibly because the associated code transmitteris transmitting a codeto the dispatchers ofiice at-that particular time. Thetreading of the train in question upon the detector track circuit containing track relay 5DR causes this relay SDR to be de-energized, the pick up relay P117 to be operated to the reverse dotted position,:and the red-stick relay RS to -be picked up and stuck up, in a manner as'already described above. With ,the red stick relay RS picked up the energizingcircuit for the red cam relay RK including inseries therewith the {motor M, heretofore traced,-is completed. Although the completion of this circuit causes the code transmitterGI' to begin to operate, and thereby causes reversal of contacts 9,6--| 25, which .contacts 9624,25 reverse the polarity applied to-the upper winding of the ,pilotrelay PR thereversal-of the current how in the upper winding of the relay PR. at this time will not affect the polarized armatures of this relay PR3, because the lower winding of this relay ,is'nowenergized by excess current, by reason of theiactthat the battery M associated with the ,;pilot relay PR is ,now connected in the look-out circuit LO so as -to increase the current flow therein by reason of the accumulated effect of the batteries 14 and -80. The code transmitter 0T operates through one or more successive cycles without transmitting a code, because the synchronizing relay SYN is not picked up inspite of1 closure of the contacts I130 operated by the starting carn 'STC at thebeginning of each cycle, this energizing circuit for relay SYN being broken at the contact I 12 of the pilot relay BB Alsonitshouldbe {noted that the code transmitter is not stopped at the end of its first, or any other, cycle of operation, by reason o O enin -o p o ta t pe a -by stop 99 K158. Although this contact H4 is opened at the ,end of each ,cycle, it does not open the stick curcuit for the red stick relay RS because the other branch of this stick circuit for relay RS including the .contact 1| 12 is intact and the relay R5 remains stuck up.

Let us now assume that at substantially the middle of the= c ycleo f operation of the .code transmitter'QT- the pilot relay PR is picked up, possibly because the code transmitting apparatus assoc at d herewith ha com l e its code ran mitting function. This picking up of the relay PR at an intermediate point in the cycle of the operation of the code transmitter C'I causes the relay BB to he (lo-energized, :(no excess energy xi t n in the l k-01 i i cu LO at i nd w th t e nchronizin relay s n de -e ized (th pil t rela h v n dr pp du n an intermediate part of a cycle) the following circuit for the hold over relay H0 is completed:beginning at the terminal l5! of the suitable battery, back contact H2 of the pilot relay PR wires NH and ISL-winding of the hold-over relay H0 wire I82, back contact I83 of the relaySYN assuming its de-energized condition, to the negative terminal N of the said battery. With the hold-over re a E0 ne i ed, th f low p me stick circuit for the red stick relay RS is completed:='-,begi;nning at the terminalB .of a suitable battery from contact J85 of the hQIdv-QVBI' relay H0 WDPQS J 5 and 1-9;, front stick contact I01 o the re st ck r a B wires 10,6 an 6 7.5

winding of the pilot relay PR is directly con-.

nected with the battery containing terminals B and N through contacts 99 and I23, so that the upper winding of the pilot relay PR is supplied with bucking current tending to hold the polarized armature and associated contacts 15, 96, 93 and N2 of this relay PR in their retracted position, in spitev of the shifting of the contacts 95 and E25 associated with the hold-over cam HOC of the code transmitting mechanism at the end of the cycle under consideration.

As the code transmitter CT now continues its operation and begins the next cycle, the starting cam STC closes its contact I30, and in. so doing picks up the synchronizing relay SYN through a circuit heretofore traced. The picking up of the synchronizing relay SYN breaks the energizing circuit for the hold-over relay H0 thereby re-.

establishing a circuit for the upper winding of the pilot relay PR which includes the contacts 96-425 of the hold-over cam HOC. With the synchronizing relay SYN now energized the code transmitting circuit is completed at the contact N6 of this relay SYN the specific code of impulses necessary to close selector contact ill of relay (IRE is then transmitted to the tower to cause the red lamp R to be energized in a manner and for reasons already explained. With the hold-over relay HO now again de-energized it will not be able to permit theoperation of the code transmitter CT to be carried past the point at which the contacts 96l25 assume their left hand position. The pilot relay PR is therefore re-energized at the end of this cycle of operation of the code transmitter 0T due to shifting of contacts Q5-l25 and opening of contacts lid, and all of the apparatus associated therewith is returned to its normal condition, in which it has been shown.

In the particular embodiment of the invention illustrated the coding wire comprises the telephone line TEL simplexed. This simplexing of the telephone line is accomplished by bridging impedances l5, l5, Ni etc. across the telephone line, and in connecting the circuit portions of the coding circuit to the midpoint of these impedances. It is of course understood that due to neutralization the coding impulses in an arrangementof this kind the impulses will 'not interfere with simultaneous telephone communication. On the other hand, if desired, the coding circuit may comprise. a separate line wire and the common return wire C, if desired.

In the specific dispatchers office equipment illustrated in Fig. 1A of the drawings the relays RG and RR if once picked up remain, stuck up until manually restored. If automatic restora tion or de-energization is desired, the stick circuit (see Fig. 2) for the relay RG may be carried through back contact I of the relay R3 and similarly the stick circuit for the relay RR may be carried through a back contact I96 of the stick relay RG Suitable single stroke audible signals GA and RA, which sound only upon being energized may be connected in series with the lamps R and G if desired. With this modified construction the lamps R and G of the miniature track layout would at all times indicate the condition of occupancy of the corresponding detector track circuit, and the audible signal would .sound upon each change of indication. This modified form'of the circuit arrangement for the relays RG and RR has been shown in Fig. 2 of the drawings.

Further it should be understood that, even though in the arrangement shown provision has only been made for the indication of occupancy of detector track circuits associated with track switches, the form of indication illustrated may be carried much further. For instance, any other track circuit may be indicated in the same way; and further if desired the position of track switches and derails, and the indicating condition of signals may be indicated in the same way.

It is of course noted that the lock-out arrangement including the. pilot relays PR prevents two codes being transmitted to the dispatchers office at the same time. Also, as heretofore pointed out, the cut-out relays COR located in the tower prevents an OS-ing code being transmitted from a waystation to the dispatchers office at a time when the dispatcher is transmitting a control code to one of the waystations. This cutout relay COR, of course, by itself is not able, to prevent the dispatcher from transmitting a control code when an OS-ing code is being received, and for this reason the operator must assure himself that there is no OS-ing code eing transmitted when he starts to transmit a control code. 'This may be accomplished by listening in on a telephone connected across the coding circuit, or in any other suitable or practical way. On the other hand, if desired, instead of using the cut out relay COR a pilot relay PR may be used, which has contacts associated therewith which open all of the circuits leading to the dispatchers calling key or. lever code cont cts, so that the dispatcher can not transmit a control code when excess energy exists in the look-out circuit LO.

Referring to Fig. 1B of the drawings the dotted polygon GT is intended to conventionally represent the OS-ing mechanism associated with the track switch S and the rectangle 20! is intended to conventionally represent the control mechanism for controlling the switch machine and signals associated with the switch S It should be understood that the present invention is also applicable to double track systems and that cross-overs may be operated in substantially the same way as single end switches are operated, suitable approach locking of course being used in each case in a manner and for reasons indicated in the application heretofore referred to. It may also be pointed out here that instead of using a metallic common return wire C, as shown, ground plates or cones and an earth return connection may be used, if desired.

Having thus shown and described one specific embodiment of a portion of a train dispatching system embodying my invention in which certain parts .and devices have been shown conventionally, it is desired to be understood that the particular arrangement illustrated has been selected for the purpose of enabling the features of the invention to be described, and has not been selected with the intent of showing the scope of the invention or the particular apparatus preferably employed in practicing the same; it is therefore desired to be understood that various changes, modifications and additions may be made to adapt the invention to the particular signalling system and the particular track layout where the invention is to be practiced, all without departing from the spirit or scope of the invention or idea of means underlying the same, except as demanded by the scope of the following claims.

What I claim as new is:

1. In an OS-ing system for indicating the condition of occupancy of a plurality of track circuits of which more than one of said track circuits may become occupied or unoccupied simultaneously, the combination with a railway system, of a plurality of track circuits each including the usual track relay and track circuit source of current, a single line circuit associated with all of said track relays and a local ofiice, code responsive means at said office for giving an indication depending on the character of code received oversaid line circuit from one of said track circuits in response to a change in the condition of its track relay, code impulse sending means located at each of said track circuit locations for transmitting to sai-dcode responsive means over said line circuit distinctive electric code impulses upon each change in the condition of the corresponding track relay, and a lockout circuit and associated relays active when one code impulse sending means is active to pre: vent all other code impulse sending means from sending any impulses over said line circuit.

'2. In combination with a railway system, a plurality of Way stations located at different remote points along a railway track, a local dispatchers oflice, a line circuit connecting said way stations and oflice, code responsive selecting relays in said ofiice, a lockout circuit connecting all of said way stations and office, an automatically operated transmitting means located at each of said way stations comprising; a motor driven code transmitter for intermittently completing said line circuit to simulate a code for each cycle of operation thereof, a normally energized lockout relay in said lockout circuit for preventing a code being transmitted by said transmitter, means for energizing said lockout circuit with excess energy in response to movement of a particular lockout relay to its retracted position, said excess energy being suificient in value toprevent any other lockout relay being moved to the retracted posi: tion, and means for initiating said code trans mitting means and causing said lockout relay to assume its retracted position.

3. In combination with a railway system, a plurality of way stations located at difierent remote points along a railway track, a local dis; patchers off ce, a line circuit connecting said way stations and ofiice, code responsive selecting relays in said ofiice, a lockout circuit connecting all of said way stations and ofilce, an automati cally operated transmitting means located at each of said way stations comprising; a motor driven code transmitter having a plurality of separate interrupters each of which is adapted to intermittently complete said line circuit in code fashion for each cycle of operation thereof if selected, a normally energized lockout relay in said lockout circuit for preventing a code being transmitted by said transmitter, means for energizing said lockout circuit with excess energy in response to actuation of a particular lockout relay to its retracted position, and means for selecting one of said interrupters, initiating theassojciatedycqde transmitting means and causing the associated lockout relay to assume its retracted position in response to a change of traiiic conditions.

4. In combination with a railway system, .a plurality of way stations located at different remote points along a railway track, a local dispatchers ofiice, a line circuit connecting said way stations and office, code responsive selecting relays in said oflice, a lookout circuit connecting all of said way ta on a d Qfiiq a a i ma ical r 'td code transmitting means located at each of said way stations comprising; a motor driven code transmitter for intermittently completing said line circuit to simulate a code for each cycle of operationthereof, a normally energized lockout relay in saidlockout circuit for preventing a code being transmitted by saidtransmitten'm'eans for energizing said lockout circuit with excess energy in response to movement of a particular lockout relay to its retractedposition, said excess energy suff cient in value to prevent any other lockout relay being moved to the retracted position, means for initiating said code transmitting means and causing said lockout relay to assume its retracted position, and means for stopping said code transmitter after one complete code of impulses has been transmitted.

5. In combination with a railway system, a plurality of way stations located at diiferent remote points along a railway track a local dispatchers ofiice, a line circuit connecting said way stations andofiice, code' responsive selecting relays in said ofiice, a lookout circuit connecting all of said way stations and oifice, an automatically operated code transmitting means located at each of said way stations comprising; a motor driven code transmitter having a'plurality of separate interrupters each of which is adapted to intermittently complete said line circuit in code fashion for each cycle of operation thereof if selected, a normally energized lockout relay in said'lockout circuit for preventing a code being transmitted by said transmitter, means for energizing said lockout circuit with excess energy in response to actuation of'a particular lockout relay to its retracted position, means for selecting a particular interrupter of said code transmitting and for initiating said code trans mitting means and for causing said lockout relay to assume its retracted position, and means for stopping said code transmitter at the end of its operating cycle as soon as abomplete code has been transmitted since its initiation.

6. In combination with a railway system, a plurality of way stations located at different remote points along a railway track a local dispatchers office, a line circuit connecting said way stations and oiilce, code responsive selecting relays in said oflice, a lockoutcircuit connecting all of said way stations and oflice', an automaticallyoperated transmitting means: located at each of said way stations comprising; a motordriven code transmitter having -a plurality of separate interrupters each of which is adapted to intermittently complete said line circuit in code fashion for each'cycle of operation thereof if selected; a normally energized lockout relay in said lockout circuit for preventing a code being transmitted by said transmittenmeans for energizing said lockout circuit with excess energy in response to actuation of 'a particular lockout relay to its retracted position, a motor driven code trans mitter for intermittently completing said line circuit for each cycle of operation thereof, traffic controlled means for initiating said code transmitter, a normally energized lockout relay 'in said lockout circuit for preventing a code being transmitted by said code transmitter in spite of its operation thereof, said lockout relay being urged to its retracted position in response to operation of said trafiic controlled means but assuming its retracted position only in the event said loqkout circuit is not energized by excess current, means for energizing said lockout circuit by excess current upon the retraction of one of said lockout relays, means for stopping said code transmitter at the end of the first cycle of operation during which a code is being transmitted, andother means for allowing said code transmitter to operate through an additional cycle of operation in the event that the lockout relay is held in its normal position by excess energy and is allowed to assume its retracted position during anintermittent point in the cycle of operation of said code transmitter.

7. OS-ing means for railway systems comprising, two indicators, a stick relay for each of saidindicators, said indicators being located in a dispatchersoffice and if active indicating respectively the occupancy and unoccupancy of a distant track circuit, a code responsive selecting relay having contacts associated therewith of which one is momentarily closed to pick up one of said stick relays in response to one distinctive code and then another contact is momentarily closed to pick up the other stick relay in response to another distinctive code, a track relay for said distant track circuit, other transmitting means for transmitting one distinctive code upon de-energization of said track relay and for transmitting another distinctive code upon energization of said track relay, and a back contact for eachof, said stick relays in the stick circuit of the other stick relay, whereby the picking up of one stick relay automatically drops the other stick relay. v

8. In an O S-ing system for indicating conditions of traffic along a railwaytrack, the combination with a railway track, of a plurality of way stations along said track, a local dispatchers ofiice, a line circuit connecting all of said way stations andsaid office, means at each of said way stations for transmitting a distinctive code of impulses to said office in response to conditions of traflic at such. way station, code impulse responsive means at said ofiice for giving an indication depending on the character of the code of impulses received, and lockout means for preventing a code of impulses being transmitted from one way station while a code of impulses is transmitted from another way station including a normally energized relay at each way station which if energized by excess current will prevent said way station transmitting a code of impulses.

9. In a train dispatching system, the combination with a plurality of way stations and a dispatchers office, of a track circuit at each way station including a normally energized track relay, two stick relays associated with each of said track relays, a' pick-up circuit for each of said two stick relays, means for momentarily closing one of said pick-up circuitswhen the associated track relay is de-energized and for momentarily closing the other pick-up circuit when the associated track relay is energized,,a stick circuit for each stick relay, and means for indicating in the dispatchers" oificethe condition of energization of said stick relays.

-10. In a train dispatching system, the combination with a plurality of way stations and a dispatchers office, of a track circuit at each way station including a normally energized track relay, two stick relays for each of said track relays, a

pick-up circuit for each of said two stick relays,

means for momentarily closing one of said pickup circuits when the associated track relay is deenergized and for momentarily closing the other pick-up circuit when the associated track relay is energized, a stick circuit for each stick relay,

means for indicating in the dispatchers ofiice the condition of energization of said stick relays, and means for breaking said stickcircuits when the condition of said stick relays has been indicated in said ofiice.

11. In a system for controlling track switches, a central ofilce, a distant way station, a track switch at said way station, a switch machine for operating said track switch, a'telephone line connecting said ofilce and switch'machine and having a telephone receiver at said central oflice, a control circuit for operating said switch' machine, and means associated with said switch machine for intermittently applying current characterizing a particular code to said telephone receiver While said switch machine is operated from one to the other extreme position.

12. In a system for controlling track switches, a central office, a distant way station,'a track switch at said way station, a switch machine for operating said track switch, a telephone line connecting said ofiice and switch machine and having a telephone receiver at said central oflice, a control circuit for operating said switch machine, and means associated with said switch machine for intermittentlyapplying current to simulate a particular code to said telephone receiver while said switch machine is operated from one. to the other extreme'position.

13. In a system for controlling track switches, a central oflice, a distant way station, a track switch at said way station, a. switch machine for operating said'track switch, a telephone line connecting said oflice and switch machine and having a telephone receiver connected to the ofiice end thereofQa control circuit'consisting of said telephone line simplexed and a'oommon return wire for controlling the operation of said switch machine, and means associated with said switch machine for intermittently applying current to said telephone receiver while said switch machine is operated from one to the other extreme position.

14. Ina system for controlling track switches, a central ofiice, a distant way station, a track switch at said way station, a switch machine for operating said track switch, a telephone line connecting said ofiice and switch machine and having a telephone receiver connected to the office end thereof, a control circuit consisting of said telephone line simplexed and a, common return Wire for controlling the operation of said switch machine, and means associated with said switch machine for intermittently applying current to simulate a particularcode to said telephone recontrol circuit for said polarized relay controlled by a, front contact of said normal control relay,

a reverse control circuit for-said polarized relay controlled by a front contact of said reverse control relay anda back contact of said normal control relay, and means for operating said switch to its normal or its reverse position according as said polarized relay' is energized in the normal or the reverse direction. I

16. In a centralized traffic control system for railroads, a plurality of traffic controlling signals for establishing a corresponding number of routes over a trackway, a plurality of neutral relays one for clearing each route and one for all routes at stop, energizingcircuits for each of said the corresponding route is energized and that route is set up over the trackway, means for selectively energizing any particularneutral relay,

and means allowing only one of said neutral relays to be energized at a time, whereby any route may be cleared, and whereby any cleared route may be put to stop.

' 17. In a dispatching system for railroads, a track switch, a plurality of signals governing trafiic over said track switch, a route storing relay for each of said signals, a stop route relay, a dispatchers ofilce, a code transmitting means manually govemable in said dispatchers oflice for transmitting any one of a plurality of series of code impulses, code receiving means at said track switch for selectively energizing a particular route storing relay or said stop route relay in accordance with the particular one of said plurality of series of code impulses, a stick circuit-for each route storing relay including its own front contact and a back contact of said stop route relay, and a circuit closed by each route storing relay when energized for clearing its associated signal only when said track switch is in alignment for the corresponding route.

18. In a centralized railway traific controlling system of the selector code type, the combination with a relay having a control winding and a holding winding, a circuit for said control winding including a source of direct current, a circuit for said holding winding including a ,front contact of said relay and a source of direct current of fixed polarity, whereby if said holding circuit isclosed the closing of said control circuit will result in de-energization of said relay if said first mentioned source is of a particular polarity.

19. In combination, a railway track switch having a normal and a reverse position, a normal control relay for said switch, a reverse control relay for said switch, a polarized relay having contacts which are operated to a position depending on the polarity of the current temporarily applied to the relay and which remain in said position until current of reverse polarity is applied to the relay, a normal control circuit for said polarized relay controlled by a front contact of said normal control relay, a reverse control circuit for said polarized relay controlled by a front contact of said reverse control relay and a back contact of said normal control relay, and means for operating said switch to its normal or its reverse position according as said polarized relay is energized in the normal or the reverse direction.

20. In a centralized traffic control system for railroads, a track layout including a track switch for establishing a plurality of routes through said track lay-out, a switch machine for operating said track switch, a signal at the entrance point toeach route for when indicating proceed allowing a train to move over said route, a route relay for each route, a circuit for operating said switch machine to a, position to establish a particular route closed only if the corresponding route relay is energized, a circuit for causing'a particular signal to indicate proceed closed only if the route at the entrance to which saidv signal is located is. established and then only if the corresponding route relay is energized, and means for manu-' ally controlling said route relays.

21; In a centralized trafiic control system for railroads, a track lay-out including a track switch for establishing a plurality of routes through said track lay-out. a switch machine for operating said track switch, a signal at the entrance point to each route for when indicating proceed allowing a train to move over said route, a route stick relay for each route, a circuit for operating said switch machine to a position to establish a particular route closed only if the corresponding route relay is energized, a circuit for causing a particular signal to indicate proceed closed only if the route at the entrance to which said signal is located is established and then only if the corresponding route relay is energized, and pickup circuits for said stick route relays so controlled that only one of said stick route relays can be picked up at one time. 1

22. In a centralized traffic control system for railroads, a track lay-out including a track switch for establishing a plurality of routes through said track lay-out, a switch machine for operating said track switch, a signal at the entrance point to each route for when indicating proceed allowing a train to move over said route, a route'stick relay for each route, a circuit for operating said switch machine to a position to establish a particular' route closed only if the corresponding route relay is energized, a circuit for causing a particular signal to indicate proceed closed only if the route at the entrance to which said signal is located is established and then only if the corresponding route relay is energized, pick-up circuits for said stick route relays so controlled that only one of said stick route relays can be picked up at one time, and a stick circuit for each route relay including a back contact of each conflicting route relay.

23. In a. centralized trafiic control system for railroads, a track lay-out including a track switch for establishing a plurality of routes through said track lay-out, a. switch machine for operating said track switch, a signal at the entrance point to each route for when indicating proceed allowing a train to move over said route, a route relay for each route, a circuit for operating said switch machine to a position to establish a particular route closed only if the corresponding route relay is energized, a circuit for causing a particular signal to indicate proceed closed only if the route at the entranceto which said signal is located is established and then only if the corresponding route relay is energized, a control circuit connecting said track lay-outand a distant oflice, and manually operable means for controlling said route relays over said control circuit. j

24. In a centralized trafilc control system for railroads, a track lay-out including a track switch for establishing a plurality of routes through said tracklay-out, a switch machine for operating said track switch, a signal at the entrance point to each route for when indicating proceed allowing a train to move over said route,

code responsive means'for controlling-said route relays, and manually controlled means at a distantoiiice for transmitting distinctive codes to said code responsive means for controlling said code responsive means "and in turn said route relays. r

' '25; In a centralized trailic control system for 3 railroads, a track lay-out including a track switch for establishing a plurality of routes through said track layout, a switch machine for operating said track switch, a signal at the entrance point to each route for when indicating proceed allowing a train to move over said route, a route stick relay for each route, a circuit for operating said switch machine to a position to establish a particular route closed only if the corresponding route relay is energized, a circuit for causing a particular signal to indicate proceed closed only if the route at the entrance to which said signal is located is established and then only if the corresponding route relay is energized, code responsive means for controlling pick-up circuits for said route stick relays, and manually controlled means at a distant oflice for transmitting distinctive codes to said code responsive means for controlling said code responsive means and in turn said route stick relays.

26. In a centralized traffic control system for railroads, a track lay-out including a track switch for establishing a plurality of routes through said track lay-out, a switch machine for operating said track switch, a signal at the entrance' point to each route for when indicating proceed allowing a train to move over said route, a route stick relay for each route, a circuit for operating said switch machine to a position to establish a particular route closed only if the corresponding route relay is energized, a circuit for causing a particular signal to indicate proceed closed only if the route at the entrance to which said signal is located is established and then only if the corresponding route relay is energized, code responsive means for controlling pick-up circuits for said route stick relays, manually controlled means at a distant oflice for transmitting distinctive codes to said code responsive means for controlling said code responsive means and in, turn said route stick relays, stick circuits for said route stick relays, and other means controlled by said code responsive means for breaking said stick circuits.

BERNARD J. SCHWENDT. 

